Blood
Pressure Measured Over Period Of Time Best
A Clearer Picture
Needed For Physicians
Monitoring blood pressure
at home can save money and give physicians valuable insight
into a person's hypertension risk, according to a study reported
in the Journal of the American Medical Association.
The researchers note
that mixing readings at home and at the physician's office can
spot true cases of high blood pressure.
"Don't base this treatment
on one blood pressure reading in the office, because people
are living the rest of the day -the other 23 hours and 45 minutes
- and they've obviously still got a blood pressure," explains
Dr. Dennis Goodman, chief of cardiology at Scripps Memorial
Hospital in La Jolla, Calif.
"It's important to
know the average blood pressure over time," Dr. Goodman says.
Looking
at Home Blood Pressure Monitors
Sales of in-home portable
blood pressure monitors have increased dramatically as patients
play a greater role in their own health care. But few studies
have examined whether self-monitoring actually saves money or
improves patient care.
According to the American
Heart Association, 50 million American adults now suffer
from high blood pressure, a risk factor for heart attack and
stroke.
A research team, led
by Dr. Jan A. Staessen of the University of Leuven in Belgium,
divided 400 hypertensive patients into two groups. Half of the
patients received blood pressure readings during regularly scheduled
visits to their physicians, while the other half measured their
blood pressure on a daily basis at home.
One physician, treating
without access to information on whether blood pressure
readings were taken in the office or home, then made all decisions
as to each patient's treatment over a six-month period.
According to the researchers,
health-care costs for patients in the home-monitoring group
were slightly lower - just under $5 per month less per patient
on average when compared to those tested in physicians' offices.
Most of these savings
were the result of home monitoring spotting patients with what
is known as "white-coat hypertension."
"White-coat hypertension
is the transient rise in a patient's blood pressure caused by
stress in a medical environment, such as when his or her blood
pressure is being measured by a doctor or nurse," Dr. Staessen
explains.
In the absence of
outside readings, white-coat hypertension can easily lead to
a misdiagnosis of chronic high blood pressure.
Dr. Staessen estimates
that about "30 percent of hypertensive patients have this condition."
Measuring blood pressure
in the more relaxed environment of the home can produce lower
readings and spare some patients misdiagnosis and unnecessary,
expensive medication therapy.
Physicians
and Patients Working Together
However, the study
found that relying solely on home monitoring might not be a
good idea, either. Patients in the home monitoring group had
less long-term therapeutic control over their blood pressure
than patients tested in the clinical environment, the researchers
found.
Commenting on the
study, Dr. Goodman says part of the problem is that what's "normal"
in an office-based reading may not be normal at home, because
of the influence of white-coat hypertension.
"All of these studies
that we do that show a benefit with drug therapy are based on
blood pressure measurements in the office," he says. "We really
don't have studies based on what blood pressure is doing at
home. So what is a normal blood pressure at home?"
Both Drs. Goodman
and Staessen agree that more studies need to be done to help
physicians make better treatment decisions.
The quality of many
home-monitoring kits is questioned by some experts.
"The public is a victim
to the lack of regulation in this field," Dr. Staessen says.
"Most devices for blood pressure self-measurement are being
sold without adequate instructions, [and] have not been properly
validated according to current standards."
Dr. Goodman asks his
patients to bring their monitors to his office for testing before
he approves them for in-home use.
Dr Goodman says, "The
first thing I do is tell them to go buy it, and tell the pharmacist
or whoever you're buying it from that 'I'm taking this to my
doctor, because I want him to verify that it's accurate. If
not, I'm bringing it back.'"
Many of the devices
prove inaccurate, especially those that measure blood pressure
on either the finger or the wrist.
Dr. Goodman advises
patients to stick to standard upper-arm monitors and to always
take their pressure on the same arm in the same position each
day.
Once he is satisfied
with his patients' choice of monitor, Dr. Goodman will instruct
them on its proper use and give them a personal schedule for
taking at-home readings.
"What's so helpful
about home monitoring is that patients get to see that it's
not just what you're doing in the office, they can take it themselves,"
he says. "The more blood pressure readings you can get over
the course of a day, the better."
Always consult your
physician for more information.
|
April 2004
Blood
Pressure Measured Over Period Of Time Best
Looking
at Home Blood Pressure Monitors
Physicians
and Patients Working Together
What
Is Blood Pressure?
Online
Resources
What
Is Blood Pressure?
Blood pressure, measured
with a blood pressure cuff and stethoscope by a nurse or other
healthcare provider, is the force of the blood pushing against
the artery walls.
Each time the heart
beats, it pumps blood into the arteries, resulting in the highest
blood pressure as the heart contracts.
One cannot take his
own blood pressure unless an electronic blood pressure monitoring
device is used. Electronic blood pressure monitors may also
measure the heart rate, or pulse.
Two numbers are recorded
when measuring blood pressure. The higher number, or systolic
pressure, refers to the pressure inside the artery when the
heart contracts and pumps blood through the body.
The lower number,
or diastolic pressure, refers to the pressure inside the artery
when the heart is at rest and is filling with blood.
Both the systolic
and diastolic pressures are recorded as "mm Hg" (millimeters
of mercury). This recording represents how high the mercury
column is raised by the pressure of the blood.
High blood pressure,
or hypertension, directly increases the risk of coronary heart
disease (heart attack) and stroke (brain attack).
With high blood pressure,
the arteries may have an increased resistance against the flow
of blood, causing the heart to pump harder to circulate the
blood.
According to the National
Heart, Lung, and Blood Institute (NHLBI) of the National
Institutes of Health (NIH), high blood pressure for
adults is defined as:
140 mm Hg or greater
systolic pressure
and
90 mm Hg or greater
diastolic pressure
In an update of NHLBI
guidelines for hypertension in 2003, a new blood pressure category
was added called prehypertension:
120 mm Hg –
139 mm Hg systolic pressure
and
80 mm Hg –
89 mm Hg diastolic pressure
The new NHLBI
guidelines now define normal blood pressure as follows:
Less than 120 mm
Hg systolic pressure
and
Less than 80 mm
Hg diastolic pressure
These numbers should
be used as a guide only. A single elevated blood pressure measurement
is not necessarily an indication of a problem.
Your physician will
want to see multiple blood pressure measurements over several
days or weeks before making a diagnosis of hypertension (high
blood pressure) and initiating treatment.
A person who normally
runs a lower-than-usual blood pressure may be considered hypertensive
with lower blood pressure measurements than 140/90.
Always consult your
physician for more information.
Online
Resources
(Our Organization
is not responsible for the content of Internet sites.)
American
Heart Association
Centers
for Disease Control and Prevention (CDC)
Healthfinder,
US Department of Health and Human Services (HHS)
National
Heart, Lung, and Blood Institute
National
Institutes of Health (NIH)
National
Library of Medicine
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